package org.shiwen.week1;

public class Circle {//定义了一个类叫做 Circle
    double radius;

    Circle(double radius){
        this.radius = radius;
    }

    Circle(){

    }

    void showInfo(){
        System.out.println(radius);
    }
    void printArea(double r){//定义了一个方法叫做printArea 要求输入一个参数r
        System.out.println(Math.PI*r*r);//输出圆的面积
    }
}
